1. Field of the Invention
The present invention relates to an optical touch device, and more specifically, to an optical touch device without using a reflective frame or a non-reflective frame.
2. Description of the Prior Art
In the modern consumer electronic products, a portable electronic product such as a personal digital assistant, a smart phone or a mobile phone is equipped with a touch control device as an interface for data transmission. Since consumer electronic products have become lighter, thinner, shorter and smaller, there is no space on these products for containing a conventional input device, such as a mouse, a keyboard and so on. Furthermore, with development of tablet computers focusing on humanity design, a display with the touch control device has gradually become one of the key components in various electronic products. A variety of touch control technologies, such as a resistive type, a capacitive type, an ultrasonic type, an infrared type, an optical imaging type and so on have been developing. Due to consideration for technology level and cost, the above-mentioned touch control technologies have been implemented in various fields.
For example, principle of the optical imaging design is to utilize two image capturing modules located at two corners of the display for detecting a position of an object on the display. Then, the position of the object on the display is calculated by triangulating location. Thus, compared with the conventional resistive type or capacitive type touch device, it has advantages of accuracy, high penetration, good stability, low damage rate, low cost and being capable of multi-touch, and the optical imaging design is overwhelmingly advantageous in the large-size display market. However, the conventional interrupting or imaging optical touch device needs a reflective frame or a non-reflective frame to provide the object with a background when the object is located within the coordinate detecting area, so as to isolate interference outside the coordinate detecting area. If there is a touch object on the coordinate detecting area, it will block the frame so that a sensor can sense a shadow for deriving a touch position from a shadow position.
In other words, the substantial frame is to provide functions of isolating the outside interference and being a background for the touch object. However, the substantial frame needs to be on the same plane with the sensor, resulting in difficulty in assembly and increasing manufacturing cost. But the conventional optical touch device without the substantial frame can not determine a touch point precisely due to the interference outside the coordinate detecting area. As a result, design of an optical touch device for effectively decreasing assembly difficulties and cost and for increasing determining accuracy is an important issue of the touch technology.